1. Field of the Invention
The present invention relates to a method and a device for mounting eyeglass lenses.
2. Description of the Prior Art
In a prior art method of mounting lenses, a plastics material (xe2x80x9cnylonxe2x80x9d or the like) filament is engaged in a peripheral groove in a lens and is attached at its ends to a frame which extends along the edge of the lens, usually at least along the top edge of the lens, and which has articulated branches at its ends and a central portion forming a bridge between the lenses.
This way of mounting lenses has the advantage of being light in weight, attractive in appearance, durable and easy for an optician to carry out. However, the frame portion extending along the top edge of the lenses forms a bar in the field of view of the wearer of the eyeglasses and gives a sensation of limiting their field of view.
To remedy this drawback, rimless eyeglasses have been proposed, in which articulated branches and a bridge are fixed directly to the lenses by means of screws, rivets or the like fitted into holes drilled into the lenses in the vicinity of their periphery. Rimless eyeglasses give the wearer a sensation of widened field of view, but it is relatively difficult to fit the branches and the bridge to the lenses. Because of the great diversity of lens, branch and bridge shapes and sizes, the fitter has no template for accurately marking the positions of the drilling points on the lenses. Mounting the lenses is therefore long and costly, because a relatively large number of lenses may be broken during mounting or made unusable by incorrect positioning of the holes relative to each other and to the lenses. What is more, the mounting is loose and unstable if the holes or the notches formed in the lenses are slightly oversized.
In one prior art device each articulated branch has a small lug that extends a few millimeters over the lens in a substantially radial direction and terminates in an eyelet or the like through which passes a screw or a rivet. Likewise, each end of the bridge is extended by a similar lug terminating in an eyelet through which a fixing screw or a rivet passes. For the mounting to be stable, an end of each articulated branch and each end of the bridge has another lug a few millimeters long, substantially perpendicular to the first lug and pressed onto the periphery of the lens.
To fit this device, one articulated branch and one end of the bridge are offered up to a lens, the position of the eyelets is marked on the lens with a pencil or the like, and the lens is drilled at the marked places. The positions of the eyelets must be marked with great accuracy and the lens must be drilled to the exact diameter of the fixing screws used. Otherwise, the mounting is slack and the branches and the bridge can turn relative to the lenses, which makes the eyeglasses difficult to wear and often requires the optician to start again with new lenses.
A particular object of the present invention is to alleviate these drawbacks by providing a method and a device for mounting lenses that are simple, accurate, easy to use, inexpensive, durable, light in weight and attractive in appearance.
The invention provides a method of mounting eyeglass lenses on a frame comprising two articulated branches and a bridge having at their ends means for fixing them to the lenses and a small lug adapted to extend along the periphery of the lens, in which method, on each lens, said lug at one end of said bridge is connected to said lug on one articulated branch by a plastics material filament engaged in a peripheral groove in said lens, after which said articulated branch and said bridge are fitted to said lens by drilling said lens and fitting fixing means.
The method according to the invention combines the advantages of plastics material filaments and rimless eyeglasses but avoids their disadvantages. In particular, the positions of the holes to be drilled in the lenses are marked automatically when the branches and the bridge are fitted to the lenses and secured by the plastics material filament engaged in the peripheral grooves in the lenses. After drilling the holes in the lenses, it is a simple matter, taking only a few moments, to insert fixing members into the eyelets of the branches and the bridge and the holes in the lenses.
The invention provides too a device on which eyeglass lenses can be mounted, said device comprising two articulated branches and a bridge whose ends comprise small lugs intended to extend along the periphery of each lens and means for fixing said device to said lenses, in which device, for each lens, said lugs at the ends of an articulated branch and said bridge are connected by a plastics material filament engaged in a peripheral groove in said lens.
This device has the advantage of being simple, light in weight, attractive in appearance, inexpensive and usable without special adaptation for all shapes of lenses.
In one embodiment of the invention each branch includes said lug adapted to extend along the periphery of a lens to guide or attach the plastics material filament and another lug extending over a face of the lens and including an eyelet adapted to receive lens fixing means.
Likewise, the bridge includes at each of its ends said lug adapted to extend along the periphery of a lens to guide or attach the plastics material filament and another lug extending over a face of the lens and including an eyelet adapted to receive lens fixing means.
The eyelets are preferably circular or substantially circular.
The eyelets are simply holes formed in said other lugs of the branches and the bridge.
The fixing members include screws, rivets or the like or spring clips.